Examples are directed to suppressing crack development in a surface acoustic wave (SAW) element including a double-layered IDT electrode. In one example the SAW element includes a piezoelectric substrate, a comb-shaped electrode formed on a top surface of the piezoelectric substrate, and an insulation layer formed on the top surface of the piezoelectric substrate to cover the comb-shaped electrode. The comb-shaped electrode includes a plurality of electrode fingers each having a first metal layer of a first metal formed on the top surface of the piezoelectric substrate, a second metal layer of a second metal formed on the first metal layer, and a second protective film at least partially covering the second metal layer, the second metal layer being covered by the second protective film and the first metal layer.

Embodiments of a Surface Acoustic Wave (SAW) device, or filter, and methods of fabrication thereof are disclosed. In some embodiments, the SAW filter comprises a piezoelectric substrate and an Interdigitated Transducer (IDT) on a surface of the piezoelectric substrate. The IDT includes multiple fingers, each comprising a metal stack. The SAW filter further includes a cap layer on a surface of the IDT opposite the piezoelectric substrate and on areas of the surface of the piezoelectric substrate exposed by the IDT. The cap layer has a thickness in a range of and including 10 to 500 Angstroms and a high electrical resistivity (and thus a low electrical conductivity). For instance, in some embodiments, the electrical resistivity of the cap layer is greater than 10 kilo-ohm meters (K.Math.m). The SAW filter further includes an oxide overcoat layer on a surface of the cap layer opposite the IDT and the piezoelectric substrate.

In a method of manufacturing a piezoelectric device, among a +C plane on a +Z axis side of a piezoelectric thin film and a C plane on a Z axis side of the piezoelectric thin film, the C plane on the Z axis side of the piezoelectric thin film is etched. Thus, Z planes of the piezoelectric thin film on which epitaxial growth is possible are exposed. Ti is epitaxially grown on the Z planes of the piezoelectric thin film in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film. Al is then epitaxially grown on the surface of the Ti electrode in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film.

In a method of manufacturing a piezoelectric device, among a +C plane on a +Z axis side of a piezoelectric thin film and a C plane on a Z axis side of the piezoelectric thin film, the C plane on the Z axis side of the piezoelectric thin film is etched. Thus, Z planes of the piezoelectric thin film on which epitaxial growth is possible are exposed. Ti is epitaxially grown on the Z planes of the piezoelectric thin film in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film. Al is then epitaxially grown on the surface of the Ti electrode in the Z axis direction such that the crystal growth plane thereof is parallel to the Z planes of the piezoelectric thin film.

A method for manufacturing a structure comprising a thin layer transferred onto a support provided with a charge trapping layer, the method comprising the following steps: preparing the support comprising forming the trapping layer on a base substrate, the trapping layer having a hydrogen concentration of less than 10{circumflex over ()}18 at/cm{circumflex over ()}; joining the support to a donor substrate by way of a dielectric layer having a hydrogen concentration of less than 10{circumflex over ()}20 at/cm{circumflex over ()}3 or comprising a barrier preventing the diffusion of hydrogen toward the trapping layer or having low hydrogen diffusivity; removing part of the donor substrate to form the thin layer; the manufacturing method exposing the structure to a temperature below a maximum temperature of 1000 C. The present disclosure also relates to a structure obtained at the end of this method.